Point 3 is very important: if every job sucks, it might be something about you rather than the companies you've worked for.

I've worked with people who always complain, and when an object of their unhappiness disappears, they quickly replace it with another. It's as if they were unhappy with themselves and kept projecting it elsewhere.

A string of bad luck is entirely possible. I hated my first three jobs, then the next one was okay up to a point and my current one is alright (although boring).